Download Nutrition and Microvilli Nutrition: Providing or obtaining food

Nutrition and Microvilli
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Nutrition: Providing or obtaining food necessary for health and growth.
a. Four steps: Ingestion, Digestion, Absorption, and Elimination
Microvilli: One of the many fine, fingerlike projections of the epithelial cells in the lumen of the
small intestine that increase its surface area.
a. Function: Serve the purpose of increasing surface area so that there can be a greater
surface area so that there can be more transport of nutrients and materials across cell
plasma membranes. Inside the microvilli there are actin filament bundles and blood
vessels and lymphatic vessels that create the lacteal. The lacteal is responsible for the
pumping of the lymph fluid out of the villi.
b. Mammals have microvilli
In the digestive system, microvilli depend on:
a. Stomach: The stomach breaks down food broth both mechanically and chemically by
churning and secreting gastric juice which breaks down food with enzymes.
b. Liver: The liver produces bile which helps breakdown fats with bile salts.
c. Pancreas: The pancreas produces an alkaline solution rich in bicarbonate which acts as a
buffer to balance the acidity of chime. It also produces proteases (hydrolytic enzymes)
that help break down proteins. These features protect the microvilli and absorb food.
Some organism do not have microvilli; they survive by other mechanisms:
a. Unicellular organisms: Amoeba use phagocytosis to engulf food into vacuoles; when
food is needed, chemicals are released into the vacuole to break down food and then
the particles diffuse into the cytoplasm.
b. Plants: Trumpet hyphae in bryophytes are autotrophs so they can make their own food.
They also obtain nutrients from either diffusion from the atmosphere or absorption
from the soil. They have root hairs to increase surface area. Some plants have a
symbiotic relationship with bacteria to covert atmospheric nitrogen into a usable form
the plant. Plants also have a vascular system that consists of xylem and phloem that
transport nutrients and water.
c. Animals: Hydras and sponges absorb nutrients through either a gastrovascular cavity or
intracellular digestion. The walls of the cavity excrete digestive enzymes that break
down food and are then absorbed into the nutritive muscular cells. Sponges only use
intracellular digestion which is taking in food by endocytosis and storing it in a food
vacuole that binds with a lysosome which break down nutrients with enzymes.
How Nutrients are transported to the circulatory system
a. Nutrients move into the blood stream at the microvilli due to the fast rate of
absorptions, though this is only carbohydrates and proteins that go into capillaries. Fatty
acids and Glycerol go in through the lacteal in the villi they go through the tubes and
sooner or later will end up in the blood stream.
How the Digestive System depends on other body systems
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a. The circulatory system is a network of arteries, veins, arterioles, venules, and capillaries
that work to deliver the nutrients that were absorbed in the digestive tract to the rest of
the body.
b. It depends on the muscular system because smooth muscle in the esophagus, stomach,
small and large intestines, and rectum contain muscle that contracts and moves food
along the process of nutrition.
c. It depends on the urinary system to expel waste products and cleans the blood of waste
products produced by the digestive system.
Disruptive Digestive Diseases
a. Lactose Intolerance
i. Cause: low levels of lactase enzyme in small intestines
ii. Symptoms: diarrhea, nausea, cramps, bloating and gas
iii. Treatment: Take lactase enzyme or avoid dairy products
b. Celiac Disease
i. Cause: genetic
ii. Symptoms: gluten intolerance, vomiting, bloating, diarrhea
iii. Treatment: gluten free diet
For more information:
http://www.rsd.edu/schools/carmichael/masters/pdf/hwsystmswrky.pdf
http://digestive.niddk.nih.gov/ddiseases/pubs/yrdd/
http://digestive.niddk.nih.gov/ddiseases/a-z.aspx